1. Division of Epidemiology and Biostatistics, School of Public Health, University of Illinois at Chicago, Chicago, IL, USA
2. Nyanza Reproductive Health Society, Kisumu, Kenya
3. Division of Global HIV/AIDS and Tuberculosis, Centers for Disease Control and Prevention, Atlanta, GA, USA
4. Division of Global HIV/AIDS, Centers for Disease Control and Prevention, Kisumu, Kenya
5. Departments of Medicine, Global Health, and Epidemiology, University of Washington, Seattle, WA, USA